It is already known in the art to provide methods and compositions for the electroless deposition of metallic silver on various substrates, such as glass plate in the manufacture of mirrors, and on other glass objects such as Christmas tree ornaments, etc.
The patent to Sivertz et al U.S. Pat. No. 3,776,740, granted Dec. 4, 1973, discloses one method for the electroless deposition of silver, utilizing a reducing agent in the form of an aldonic acid such as gluconic acid, for example. It is pointed out in the Sivertz et al patent that various mild reducing agents have been used, such as formaldehyde, glucose or invert sugar, but that the use of these materials have caused problems in the art, particularly since the silvering solutions are short-lived and the reducing agents tend to be unstable, often evolving hydrogen or decomposing to form sludge or interfering products. Using the method of the Sivertz et al patent, the components of the silvering solution are brought together just before contact with the substrate to be silvered. This may be achieved, for example, by pouring or pumping the component solutions such that they meet just before contact with the substrate. Alternatively, the component solutions may be air-atomized or hydraulically sprayed prior to or simultaneously with intermixing at the surface of the substrate. Othr reducing agents such as dextrose, fructose, arabinose nd invert sugar are referred to in the disclosure of the Sivertz et al patent.